Hitoshi's alien mother and alien father
He arrived to Earth via his spaceship run by an artificial intelligence named Jan Pu, but crash lands on the surface where Hazumu is, killing him instantly. Hitoshi rectifies this by regenerating Hazumu, but unexpectedly changes his physical sex in the process.
This is a mystery to Hitoshi for some time until he is finally able to confirm that Hazumu's "life grain" count is slowly dissipating, and by the time Hitoshi confirms this, Hazumu only has one month left to live. Hitoshi originally came to Earth as a cultural anthropologist and to study the emotions of the human race since his species has long-since given up any emotion at all. Hitoshi recounts that at the peak of his people's civilization, they had discovered the means to destroy all life in the entire universe instantly, so in order to prevent this from ever happening, his people chose to discard their emotions.However, even after becoming a calm, logical race where emotional clashes such as violence and war disappeared completely, his people also started to lose their sexual urges in order to propagate his species further. In their current situation, if something is not done soon, his entire species will soon become extinct, which is why he is on Earth to find a way to save his species. He arrives at the conclusion that his species needs to remember how to love each other in order to survive, so love becomes a focus of his research. In order to observe humans more closely, along with Hazumu and her ongoing relationship with Yasuna and Tomari, Hitoshi starts working at Hazumu's school as a biology teacher, and inadvertently becomes the target of Namiko's extreme affections.
Hitoshi has an utter lack of human customs and way of life, and due to this unfamiliarity, his comments often provide the series with an outside perspective on love. More than anything else, Hitoshi is constantly butting in on Hazumu's love affairs, which greatly annoys her to no end as the series progresses. Throughout the series, his views on other subjects such as friendly competition or war provide a somewhat existentialist point of view. Hitoshi continuously follows Hazumu around during outings with his friends in order to further observe her and her friends.